1. Field of the Invention
The present invention is directed generally to a double safety magnetic valve and more particularly to a double safety magnetic valve with two valves being accommodated in a housing.
2. Description of Background of the Invention
A double safety magnetic valve of this kind became known, for example, by the DE 195 25 384 A1. Such double safety magnetic valves are used in particular as safety magnetic valves on the gas input side of gas heat generators.
In the double safety magnetic valve known from the DE 195 25 384 A1 the two valve disks are disposed axially on top of one another in a housing and each cooperates with its own valve seat. The valve disks are each part of two adjustment elements independent of each other, the second of which is guided axially displaceably in the first. Both adjustment elements are opened by a common magnetic drive each against the action of a closing spring, wherein the two closing springs perform the closing stroke of both valve disks completely independent of one another when the magnet is switched off. Thus the safety requirements for gas safety valves can be met.
Although a compact construction has been enabled with the known double safety magnetic valves and thus on one hand a space-saving and on the other hand substantially cheaper producable unit, the axial overall height is still relatively large due to the valve disks and adjustment elements which are axially displaceable as well as disposed behind one another. Due to the ever increasing miniaturization, generally a further reduction of dimensions of the known double safety magnetic valve and in particular of its axial height is aimed at. Furthermore, mounting of the known double safety magnetic valve is very difficult since the valve disk, being the second one in flow direction of the double safety magnetic valve, must be threaded through the valve opening of the first valve disk.
It is hence the object of the invention to design a double safety magnetic valve of the aforementioned type even more compact in axial direction (opening direction).
According to the invention this object is solved in a manner which is equally surprisingly simple and effective in that the outer (first) valve disk, being the first one in flow direction of the double safety magnetic valve, surrounds the inner (second) valve disk and both their valve seats are combined to a common valve seat, which surrounds the only valve opening, and the second (inner) closing spring of the inner (second) valve disk is supported on the outer (first) valve disk or on an adjustment element thereof.
In contrast to the double safety magnetic valve known from the DE 195 25 384 A1, two valve seats do not have to be machined with high expenditure of time and labor, but only one single valve seat. Mounting of the device becomes easier since the parts do not have to be brought near to two seats and a smaller device can be more easily handled. The inventive double safety magnetic valve can be produced cheaper since less machining occurs and the dimensions become smaller. In addition to the axial overall height being drastically reduced, the flow values through the inventive double safety magnetic valve (multi-functional armature) become comparable to those of a single seat valve due to the inventive reduction of both valve functions to a common seat. The inventive double safety magnetic valve can be extended to all sizes and all kinds of valves, hence with the same housing a series with several variants can be realized, for example, single magnetic valve, double magnetic valve, or multi-functional valve with various regulators.
The inner (second) closing spring of the inner (second) valve disk is supported on the outer (first) valve disk or on the adjustment element thereof, for example on a peripheral shoulder or on the base of the adjustment element of the outer (first) valve disk. The inner (second) closing spring can, for example, be disposed between the two adjustment elements, perferably in an annular gap or in an opening of the inner magnetic armature open in opening direction.
Naturally, the invention is not limited to two valves or valve disks, but can be used also for three or more valve disks disposed coaxially, which are nested into one another.
In an advantageous development of this embodiment a common flat bearing surface for both valve disks is provided on the common valve seat. This measure has the advantage that both valve seats can be produced in a single process by machining of the common, in particular flat bearing surface or bearing surface without steps.
In an alternative development two axially off-set bearing surfaces can be provided on the common valve seat for one valve disk respectively. For example, both valve seats can be constructed on different planes on the common valve seat.
For an optimal sealing effect, for a flat bearing surface an elastomer sealing means of the valve disk cooperating with said flat bearing surface is pointed or for a pointed bearing surface a sealing means of the valve disk cooperating with said pointed bearing surface is flat. All variants of the seat arrangement are possible, for example both pointed, both flat, both on the same axial height, both axially off-set to one another, each also vice versa, etc.
Further, particularly preferred are such developments of the double safety magnetic valve where a bearing surface for an adjustment element (regulator element) of a flow regulator, with the adjustment element being axially moveable in the valve opening, is also provided on the common valve seat. This measure has the advantage that three functions (two valves and one flow regulation) are brought together on one seat. The closed position of the adjustment element in the valve opening can be exactly defined by bearing on the common valve seat. The adjustment element can for example be a rod, the free diskshaped end of which extending into the valve opening bears all around on the common valve seat in the closed position.
In an alternative development a bearing or regulator surface for an adjustment element provided upstream in front of the two valve disks or valves can be provided on the common valve seat. In particular if the adjustment element engages over both valve disks in a pot-shaped manner, they are additionally covered by the adjustment element.
In order to be able to check the tightness of the inventive double safety magnetic valve a sealing check opening is provided on the common valve seat, which opens into the space between the two valve disks.
A separate guide of the inner valve disk or its adjustment disk can be dispensed with if the inner valve disk or the magnetic armature is guided axially displaceably within the outer valve disk or its adjustment element or within a guide element of the outer valve disk.
It is particularly advantageous, if the outer valve disk is motion-coupled with the inner valve disk in opening direction. Thus, the outer valve disk is also lifted from the common valve seat at the same time with the inner valve disk. In closing direction, however, both valves are not motion-coupled, for them to be able to perform their closing lift completely independent from one another.
In a development of this embodiment the outer valve disk or the adjustment element thereof can engage behind the magnetic armature in opening direction.
In order to be able to produce the double safety magnetic valve with particularly low production costs, the housing of the two valves is designed preferably as extruded profile or as a diecast part. For such extruded profiles it is also possible to laterally attach the sealing control required for gas safety valves.
Additional advantages of the invention can be gathered from the description and the drawing. Also, the previously mentioned and the following characteristics can be used according to the invention each individually or collectively in any combination. The embodiments shown and described are not to be taken as a conclusive enumeration, but have exemplary character for the description of the invention.
The invention is shown in the drawing and is more closely described by means of embodiments.